Refrigerating apparatus
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Solution Overview
Problem
In refrigerating apparatuses with a two-stage compression configuration, liquid refrigerant can remain in the intermediate heat exchanger during low outside temperatures, leading to liquid compression and instability when the system is started, affecting compressor stability.
Innovation Solution
A refrigerating apparatus with a main circuit, first and second compressors, intermediate heat exchanger, condenser, expansion valves, receiver, evaporator, three-way valves, bypass passages, check valves, and solenoid valves, allowing controlled refrigerant flow to recover liquid refrigerant to a receiver, preventing liquid compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an intermediate heat exchanger is provided in a two-stage compression configuration, then the efficiency of the refrigerating apparatus is improved, but liquid refrigerant may remain in the intermediate heat exchanger when outside air temperature is excessively low, causing liquid compression and affecting compressor stable operation
Solution Approach 1:
The system performs preliminary action by using the first compressor to suction and remove liquid refrigerant from the intermediate heat exchanger before the liquid can cause compression damage. The control unit activates the first compressor specifically to evacuate liquid refrigerant when low temperature conditions are detected, preventing the harmful effect before it occurs.
Solution Approach 2:
The first compressor acts as an intermediary device between the intermediate heat exchanger and the second compressor. It serves as a protective mediator that removes liquid refrigerant from the intermediate heat exchanger, preventing the liquid from reaching and damaging the second compressor while maintaining the efficiency benefits of the intermediate heat exchanger.
2Productivity
If a two-stage compression configuration is adopted, then the output of the refrigerating apparatus is improved, but liquid compression occurs when liquid refrigerant is sent to the high-pressure side compressor, affecting stable operation
Solution Approach 1:
The control unit performs preliminary action by detecting low outside air temperature conditions and activating the first compressor to remove liquid refrigerant from the intermediate heat exchanger before the two-stage compression process begins, preventing liquid compression damage while maintaining high productivity.
Solution Approach 2:
The control unit implements feedback control by monitoring outside air temperature and system conditions, then adjusting the operation of the first and second compressors accordingly. When liquid refrigerant is detected or temperature conditions indicate risk, the control unit activates the first compressor to remove liquid, ensuring stable operation while maintaining high output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Stabilizes compressor operation by effectively removing liquid refrigerant from the intermediate heat exchanger, reducing the risk of damage and ensuring stable operation.
Implementation Method 1
a check valve that is provided in the first bypass passage and allows the refrigerant to flow only in a direction from the three-way valve toward the receiver
Implementation Method 2
a first solenoid valve that is provided in the second bypass passage and switches over to an open state of the second bypass passage
Implementation Method 3
an intermediate heat exchanger that is disposed between the first compressor and the second compressor
Implementation Method 4
a condenser that is disposed on a downstream side of the second compressor
Implementation Method 5
In the condenser, heat exchange between the refrigerant and air is performed, and the refrigerant becomes a high-temperature and high-pressure liquid refrigerant
Implementation Method 6
an evaporator that is disposed on a downstream side of the second expansion valve
Implementation Method 7
by exchanging heat with air in the evaporator, the refrigerant becomes a low-temperature and low-pressure gaseous refrigerant
Implementation Method 8
by passing through the expansion valve, the temperature and pressure of the refrigerant are lowered
Data Source
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AI summary
There is provided a refrigerating apparatus (100) that can be operated more stably. The refrigerating apparatus (100) includes a first compressor (1) and a second compressor (2) that are arranged in series on the main circuit (90), an intermediate heat exchanger (3), a condenser (4), a first expansion valve (5), a receiver (6), a second expansion valve (7), an evaporator (8), a three-way valve (9) provided between the intermediate heat exchanger (3) and the second compressor (2), a first bypass passage (10) that couples the three-way valve (9) and the receiver (6), a second bypass passage (11) that couples the receiver (6), the three-way valve (9), and the second compressor (2), a first solenoid valve (13) that switches over to an open state of the second bypass passage (10), and a second solenoid valve (11) that is provided between the receiver (6) and the second expansion valve (7) and switches over to an open state of the main circuit (90).